1. Field of the Invention
The present invention relates to a tilting pad bearing.
2. Description of the Related Art
A slide bearing is a bearing that carries a rotating shaft via a thin fluid film. Such a slide bearing exhibits higher withstand load performance in comparison with a rolling bearing and is also superior in vibration damping and impact resistance. For this reason, slide bearings are widely employed for industrial large machinery such as steam turbines and generators which need to provide high reliability. As one of the slide bearings used for such industrial large machinery, tilting pad bearings are known in the art which is superior in vibrational stability.
A tilting pad bearing includes a plurality of pads arranged in a circumferential direction of a rotating shaft, and a bearing housing which carries the plurality of pads via a plurality of pivots in a tiltable manner. Lubricating oil is fed between the rotating shaft and sliding surfaces of the pads to form oil films therebetween, with the pressure by the oil film carrying the rotating shaft. In this case, the tilt of the pad varies according to the pressure distribution of the oil film, which can suppress unstable vibration such as oil-whip.
The provision of the tilting pad bearings are generally based on an oil bath method or a direct feed method. In the oil bath method, the seal performance of a bearing chamber in which to house pads is enhanced and lubricating oil is stored in the bearing chamber. With this, the lubricating oil is adapted to be fed between a rotating shaft and sliding surfaces of the pads. If the oil bath method is adopted, however, part of the lubricating oil heated to high temperature by heat generation due to shearing will stay in the bearing chamber. In such a case the metal temperature of the pad may rise.
On the other hand, the direct feed method allows lubricating oil to be fed between a rotating shaft and sliding surfaces of pads via an oil-feeding hole formed in the pad (see e.g. JP-5-36646-B). In this method, since low-temperature lubricating oil is directly fed between the rotating shaft and the sliding surfaces of the pads, a rise in the metal temperature of the pad can be suppressed. In addition, an amount of lubricating oil fed thereto can be reduced.